package Task34;

import java.util.Scanner;

public class Main2 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()){
            int sd = scanner.nextInt();
            int ed = scanner.nextInt();
            long count = 0;
            for (int i = sd; i <= ed ; i++) {
                count += Feibonaqi(i);
            }
            System.out.println(count);
        }
    }
    public static long Feibonaqi(int n){
        long f1 = 1;
        long f2 = 1;
        long f3 = 2;
        if(n < 3){
            return 1;
        }
        if( n == 3){
            return 2;
        }
        int i = 2;
        while (i < n){
            f3 = f1 + f2;
            f1 = f2;
            f2 = f3;
            i++;
        }
        return f3;
    }
}
